Patients who are entered into the B27 and who agree to participate in B27.1 will have serum collected before the beginning of their preoperative chemotherapy. Serum obtained before initiation of chemotherapy will be handled according to guidelines established. After completion of preoperative chemotherapy and before surgery, another serum specimen will be obtained. A third sample will be collected 2 weeks after the definite surgery at the follow-up visit, and an additional serum specimen will be required one year after randomization. For patients whose tumors recur, a serum sample will be required at the time of breast cancer recurrence, but before any treatment for the recurrence.